#define _CRT_SECURE_NO_WARNINGS 1
class Solution {
public:
    int mySqrt(int x) {
        if (x == 0 || x == 1)
        {
            return x;
        }

        long long left = 1;
        long long right = x;

        while (left < right)
        {
            long long mid = left + (right + 1 - left) / 2;

            if (mid * mid <= x)
            {
                left = mid;
            }
            else
            {
                right = mid - 1;
            }
        }

        return left;
    }
};